Although information has been obtained on cell cycle characteristics of various human tumors, few studies have been designed to evaluate the changes that take place in tumor cell kinetics during the course of the human disease, and what effect chemo-therapy and other forms of treatment have on the kinetics of tumor growth. The current proposal will attempt to obtain information on thymidine labeling indices and other cell kinetic parameters in vivo, in a variety of human tumors prior to and after "perturbation" by conventional therapeutic procedures. One of the basic techniques used will be one of intratumoral injection of tritiated thymidine followed by fine-needle aspiration or biopsy. Such studies can be carried out in many nodules or other tumor-involved sites simultaneously or serially following treatment. Other techniques will use short term incubation in vitro of ascitic or pleural fluid and tissue slices obtained at operation. A longitudinal study in patients with ovarian cancer is planned, correlating initial cell kinetic data with response to treatment, and cell kinetic data obtained at time of recurrence. The data obtained might be helpful in predicting therapeutic response or resistance, and ultimately, in designing new treatment approaches.